270 SUMMARY OF CURRENT RESEARCHES RELATING TO 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Structure and Development. 

 "Vegetative and Reproductive. 



Anatomy of Bud-scales.* — E. Brick has studied the details of the 

 anatomic structure of bud-scales, and finds that both in origin and life- 

 history they are essentially leaf-like. The innermost bud-scales may be 

 regarded as arrested forms of foliage-leaves, but the outer scales exhibit 

 features not found in foliage-leaves, and while resembling the latter in 

 many respects, must be regarded as " divergent organs." The similarity 

 of the inner scales and the foliage-leaves concerns not only the general 

 form but also the microscopic structure of epidermis, mesophyll, inter- 

 cellular spaces, etc. The outer scales having suffered arrest at an earlier 

 stage of development show numerous differences both in form and 

 structure. The difference in development of the outer scales corresponds 

 to different morphological types, the individual types varying in the 

 presence or absence of periderm, metacutis, metaderm, phloem, scleren- 

 chyma, glands, etc. Their qualitative anatomy agrees with those parts 

 of the leaves to which they are morphologically equivalent. Suberization 

 of the scales is brought about in such a manner that the bud is enclosed 

 in a simple or complex sheath, and the dead metacutis represents a 

 physiological transition stage between metacutis and cork. In quanti- 

 tative structure the scales resemble the leaves more closely as they ap- 

 proach the axis of the bud, the greatest divergence being between the 

 outermost scales and the leaves. Thus the number and size of the 

 tracheids of the innermost scales correspond with those of the first 

 young leaves ; the vascular bundles of the outer scales show considerable 

 reduction, a fact playing an important part in subsequent development. 



Dehiscence of Anthers.t — M. Schips has studied the mechanism of 

 the opening of anthers in Lilium, Tulipa, Digitalis, etc. The present 

 paper comprises an historical summary of previous work and two sections 

 dealing with the results now obtained. The experiments of the first 

 section relate to cohesion and to the hygroscopicity of the cell-walls of 

 the fibrous tissues. It is proved that contraction of isolated cells and the 

 corresponding opening of the anther are not due to cohesion but to 

 shrinkage ; the force of cohesion is both too small and unnecessary. It 

 is also shown that the folds are entirely due to abnormal outgrowths 

 of the fibrous tissues, and that when the force of cohesion is eliminated 



* Beih. Bot. Centralbl., xxxi. (1913) pp. 209-308 (2 pis.), 

 t Beih. Bot. Centralbl., xxxi. (1913) pp. 119-208 (6 tigs.). 



